The present invention relates to means for pulling an elongated article--such as a cable, an umbilical or a pipeline--through a curved tube,--such as through the lower portion of an offshore J-tube leading from the sea bed to a surface construction, when the pulled end of the article is provided with a rigid installation head.
A pulling wire is usually attached directly to the end of the installation head and the normal pulling procedures often cause undue bending and friction damages to the head.
U.S. Pat. No. 1,672,324 describes a wire threading leader and coupler. The leader may be provided with rollers to reduce the friction between the leader and the tube walls.
U.S. Pat. No. 2,532,504 relates to a method and apparatus for installing electric cable systems. A plurality of cable conductors are connected to a pulling wire via a torque release device, a guiding, spiralling and twisting device and a swivel. The twisting device is provided with a number of friction wheels which ensures rotation of the cables.
The mentioned methods and apparatus are not suitable for the task of pulling an elongated article with a rigid installation head through a curved tube. Such a head may typically have a diameter of 150-300 mm and a length of 500-1000 mm. The diameter and radius of the J-tube can be respectively 10"-16" and 5-30 m.